Locking devices



PW-Alm M Jan. 3, 1961 @ANL ggg

B. CAMBER LOCKING DEVICES Filed July 2, 1956 LOCKING DEVICES Bernard Camber, London, England, assignor to S. & R. J.

Everett & Co. Limited, Surrey, England, a British com- Pally Filed July 2, 1956, Ser. No. 595,389

Claims priority, application Great Britain July 6, 1955 g Claims. (Cl. 12S-21S) The invention relates to a cartridge hypodermic syringe, for the medical injection of liquids, that is to say a hypodermic syringe adapted to receive a cartridge containing the liquid for injection, the contents of a cartridge in the syringe being expelled through a needle by means of a plunger.

It is an object of the present invention to provide a locking mechanism to hold the cartridge in place, and a further object is to provide a syringe in which the action of locking the cartridge in place is combined with the action required to advance the plunger rod into the cartridge -and in which the withdrawal of the plunger rod from the cartridge releases the latter to enable its removal from the syringe. This object is achieved by the provision, between an outer casing and the plunger rod, of a sleeve which is axially movable to lock over the end of the cartridge, and one or more radially movable members, for example radially movable balls, which pass through apertures dened in the said walls of the sleeve and project either into a recess dened in the inner wall of the casing (in the position in which the sleeve locks over the end of the cartridge) or into a recess defined in the plunger rod, the radially movable member or members being moved from one of the said recesses to the other when the recesses come into register during the movement of the plunger rod. During the movement of the latter into a cartridge the sleeve is moved by the plunger to the rst position and is then automatically locked to the casing, the plunger rod continuing its movement alone, and during the withdrawal of the plunger rod the sleeve is automatically released when the rod reaches the first position and is then withdrawn to the second position by further movement of the plunger rod.

It is an inherent disadvantage of cartridge syringes hitherto used that they cannot be used for withdrawing fluids as well as for injection. This arises from two causes; rstly, the plunger generally acts to push a pellet or stopper, e.g. of rubber, down the cartridge, the said pellet being unattached to the plunger and therefore not withdrawn when the plunger is withdrawn; secondly, if the plunger is attached, as by screwing, to the pellet, withdrawal of the plunger will bring about removal of the whole cartridge from the conventional container, but will not withdraw the pellet from the cartridge. Furthermore the methods so far used for securing the pellet to the plunger have not been mechanically sound and were liable to fail in operation.

In a preferred form of a hypodermic cartridge syringe according to the invention, the ball locking principle is used to cause the end of the plunger to grip the rear pellet or piston of the cartridge. l

Figure 1 is a plan view of the syringe fitted -witha bnited States Patent F An example of a locking device according to the inven- Patented Jan. 3, 196,1

ice

cartridge, part of the cartridge being broken away to show details of the plunger head and piston;

Figure 2 is an axial sectional view in elevation of the syringe and cartridge;

Figure 3 is a cross-section on the line III-III of Figure 2; and

Figure 4 is -a cross-sectional View on line IV--IV of Figure 2.

The cartridge syringe shown in the drawings includes a casing 10, one side of which is cut away to enable a cartridge 11 to be loaded into the casing from the side. Once in the casing, the cartridge is moved axially on to a double-ended needle 12, the rear end of which pierces the diaphragm of a front pellet 13 of the cartridge and places the needle in communication with the contents of the cartridge. These contents are housed between the front pellet 1 3 and a rear pellet or piston 14. A cap 15 moves axially on to the cartridge and is locked in this position in a manner to be described later, and a plunger 16 provided with a thumb stop 17 passes through the cap and engages the piston 14. As the plunger is pushed into the casing, the movement of the piston causes the contents of the cartridge to be expelled through the needle.

The manner in which the cap is locked over the end of the cartridge will now be described. The cap contains three apertures 18 in its side wall (Figures 2 and 3) in each of which is housed a ball 19 having a diameter greater than the thickness of the wall. In the position shown in Figures 2 and 3, the balls 19 project from the apertures 18 into a groove 20 in the wall of the casing 10. In this position, therefore, the cap is locked in position within the casing and the cartridge is lirmly held.

It will be seen from the drawings that the plunger has a portion 21 of reduced diameter. When the plunger is withdrawn it tends to withdraw the cap but is at rst prevented from doing so by the locking action of the balls 19 in the groove 20. A point will be reached, however, at which the waist portion 21 will be opposite the balls 19. At this point, the plunger ro-d is no longer holding the balls 19 in their locking position, and further withdrawal of the plunger causes the balls to be forced out of the groove 20 in the casing into the groove round the waist portion 21 of the plunger, and the sleeve thereafter moves with the plunger until it reaches the end of the casing. This movement of the cap releases the rear end of the cartridge and enables its removal.

To lock a new cartridge in position, the plunger is moved forward, taking with it the cap, until the cap reaches a stop or shoulder 22 in the casing, beyond which it cannot move. At this point, the forward end of the cap encloses the rear end of the cartridge, and the balls 19 are in register with b-oth the groove 20 in the casing and the groove round the waist portion 21'of the plunger. Further movement of the plunger into the casing causes the balls 19 to ride up the cam surface 23 at the side of the waist portion 21 and to enter the groove 20. The cap is now locked in position and cannot be moved in either direction, until the plunger is withdrawn.

It will be seen that, when the plunger is moved forward, it takes the cap with it until the cap reaches its locking position, at which point the cap locks to the casing and the plunger continues it movement alone. When the plunger is withdrawn, it releases the lock at a given point in its travel and then takes the cap to the rear `of the casing.

A device similar to the ball lock which has been described for the breech mechanism is used to enable the plunger head to grip the piston, so that the latter can be drawn back in the cartridge. The piston is provided with a pin-head projection, formed for example from a metal insert, having a narrow neck portion 24 and an eltlarsed. head ,25.A The. plunger rodincludes..anaxialxod 26 within a tubular member 2,7. A cylinder 28 is screwed on to the end of the tubular member 27, and a hollow cup-shaped member 2,9 is mountedgon the endoff the rod, 26 and slides within the cylinder 28.. Threeballsamare, housed in three apertures formedv ingthe side-wall ofthe cup-shaped member 29 (see Figures 2 and;-4-). A spring 31 between the, end of the tubular.l member and the rear of the cup-shaped member tends to hold the latterand-the; cylinder 28 in the relative position shown in thedrawings, in which the inner wall of the cylinder makes, contact with the outer. wall ofthe cupfshaped memberfso that the balls 30 are caused to project inwardly'and to grip; the neck portion 24ofthe piston end. To .release theepiston, a sleeve 32which surrounds theplunger rodgandzwhich is connected by a diametral pini totherodgZd, isdrawn back, against the spring 31;, towards thev thumb stop. The eifect ofV this is to cause-,therod` 2 6 and; diej-member 2,9, to movebackwards with respect to the cylinder 28 to, the; position` in which the l ballsl 3,0 are opposite; a groove 34 in theinner wall of theV cylinder 28. Qwing/to; the resistance.toA movement of the piston.. wthdrawamMhe plunger' now causes the b alls to be` forced over-thehead 25 of the piston into the groove 34, thusreleasing the piston from the plunger.

The sleeve 32,'and the thumb stop 17 are broughtgto-- gether in a similar manner when it is desired to pass the balls 30 over the head; 25 of the pistonmto enabltl :them to ygripI thewneck portion 2 4.

Themovement of thel plunger;isbrollghV aboutfby manipulating the thumb stop -in association withv the fingerl restsl35.

Theinvention is not restricted to the use ofthe ball locking system described above for connecting theplunger head to the piston, as other forms of connection, forex,- ample a screw` or bayonet fastening, can beused, Moreove rif aball locking system is used'pfor connecting the plunger headfto the piston ptherballs cangbegexpandedinto an undercut recess in the pistonorbung-instead` of Vthe: arrangement described above.

It will be clear that the syringe=which hasbeen described has the advantage that the completeoperation of the syringe, for injection and withdrawal of fluid and the1 holding and release of the cartridge, is dependent substanf tially'entirely on pushing and-pulling movementsof a: kind normal in syringe technique, theA actionbeing; to a large extent automatic.V

Theball lock gives more positive:and securegaction than devices which-have been used hithertofor connecting` the plunger head to the piston, is not Vreadily,susceptible, to wear and tear, and is relatively simple to manufacture.

I claim:

l. A hypodermic syringe or ythe like comprising a tubular casing having a lateral aperture Vthrough whichecartridge `maybe loaded intoV the syringe,gaclosure rnernfv ber at one end -of said casing, a'pluljlgergrodaxi a1 1ymovfA able, within saidl casing and passing through said cl osure; member, al-sleeve in said casing surrounding saidplunger; rod and axially slidable between a lirst position;where it locks -over one end of said cartridge and a second, posi; tion Where it is withdrawn to the rear-ofjsaid casing to ,v permit insertion and removal of cartridges, said; sleeveY having apertures in the side Wall thereof, a radially movable member which passes through said sleeve Vapertures and projects intro a recess defined inthe inner wall of saidIl casing when said sleeve isrin Vthe first position and aty other timersprojects into a recessdenedin.saiddplungerfrod, said radially movable membervbeing moved fromonelof said recesses to the other when the recesses come intofregister'during the movement of the plungerrod, and-.a stop within said casing which prevents movement Vof said sleevebeyond the position at which theradially movable g membersrare inl register with Vthe recess Yin thecasing;l

2;-.A-syringe-accordingto claim 1, inwhich saidqstopI consists-of a portion ofthe casing of-^smaller-internal l75 di mtenthallthat in. which the, sleeve, slides, the said po ion serving to support a cartridge in the syringe, the rear end of the cartridge extending beyond the end of said portion so that When the sleeve abuts against said portion it encloses the end of the cartridge.

3. A syringe according to-claiml in which said plunger rod has formed thereon .acamsurfaceadjacent said recess in the latter, said cam surface moving the radially mov ableIV member in tdthe; reessginthecasing whenthe. Inovef ment of the:v plunger. rod is;V continued after: theg engagement of said sleeve with the stop.

4. A hypodermic syringe or` the like, comprising a tubular casing having a lateral aperture through which a cartridgezmay be loaded; into; the` syringe,A ahypodermic needle mounted and projecting through one end of said casing, a closure member at the other end of said casing, a plunger rod axially movable within said casing and passing through said closure member, a sleeve in said casing surrounding said plungererod'and axially slidablebetween a rst position where itA locks over that' endf'offtheY car` tridge remote from said needle and; a second position where itiswithdrawn` tothe rear of saidv casing to permit insertion'.andremoval'of cartridges, said sleeve having apertures in the side Wall thereof, a radially: movable member whichpasses through said sleeve apertures and which projects into a recessl defined in the inner wall-of saidV casing when said sleeve is' in thevirst position andv at other times projects'into a recess defined in said plunger rod, said radially movable member being moved from one of said'recessesf to the other' when the recesses come into register during the -movement of the plunger rod, said casing Y havingV a portion of smaller internal diameter than that in which said sleeve-slideswhich serves to support a cartridge, the arrangement beingsuch that the rear end of a cartridge extends beyondI the'end of said smaller portion wherebyV when said sleeve is in said rst positlon it abuts saidv smaller portion and encloses theend of 'said cartridge:

5,. A, hypodermicsyringe-l or the like.. comprising a tubularccasing; a cartridge withinv said casing, al hypo dermic needle'mountedin andprojecting'through one end of saidcasing,y a closure Amember at the other end of said-casingg aplunger rod axially movable within said casingeand passing lthrough said closurezmember, asleeve inv saidcasing surrounding saidplunger rod' andA axially slidable -betweena'rst position where'it locksiover that` end of :said cartridge remote Afrom said needle and a second-position wherel it is-withdrawn to the rear of said in said Vplunger rodi, said radially movablevmemberbe ing'movedffrom-oneof said recesses to'thegother whenV the jrecesses'come intoregister `during the -movement of the'plunger rod, said casing Vhaving a portion of smaller internal diameter than that in which said sleeve slidesI which serves to support said cartridge, thearrangement being such thatthe-rear end of said cartridge extends beyondthe end of said smaller portion whereby when said 'sleeve is in said` first position it-abuts said smaller portion and'encloses the endy ofsaid cartridge, a piston within said cartridge, said pistonfhaving projecting therefrom a-narrow neck terminating in an enlarged head, a

plungerl head connectedto said plunger rod and'slidable within said cartridge,-said plungerihead including an' inner cylinder and an outer-cylinder slidable-relative to.

each other,saidouter'cylinderY having a recess formed in-its-inner wall Vandsaid innercylinder having `apertures in lthe iside Wallthereoffand'a yradially movablemember" which passes-through saidapertures'in said inner-cyl-` inder and projects into said recess in said outer cylinder 5 6 radially movable member moving from said recess to 2,147,616 Chaput Feb. 14, 1939 grip the neck of said piston beyond said enlarged head 2,228,585 Pletcher Jan. 14, 1941 when said cylinders are moved relative to one another 2,354,649 Bruckner Aug. 1, 1944 to another position. 2,664,086 Transue Dec. 29, 1953 6 References Cited in the le of this patent 47o 559 GFOREIGN PATENTS 9 reat Britain Aug. 17, 1 37 UNITED STATES PATENTS 620,824 Great Britain Mar. 3o, 1949 1,852,658 Kile Apr. 5, 1932 180,761 Austria Jan. 10, 1955 

